1. Field of Use
This invention relates generally to control means for a marine propulsion system of a vessel, such as a boat, ship or the like.
In particular it relates to a marine propulsion system comprising a plurality of drive systems (such as port and starboard), each of which drive systems comprises an engine having an engine throttle, a transmission having forward and reverse clutches, and a propeller shaft with a propeller thereon which is connectable to the engine by the transmission clutches. The control means comprises one or more control stations locatable at desired navigation positions aboard the vessel, and each control station comprises a plurality of sets (such as port and starboard sets) of manually operable control devices, one set for each drive system, to control the engine throttle and clutches therein.
2. Description of the Prior Art
Some prior art marine propulsion systems comprise port and starboard drive systems, each of which comprises an engine, an engine throttle to regulate the speed of the engine, a propeller shaft having a propeller thereon and a transmission to connect the engine to the propeller shaft. The transmission includes alternately engageable forward and reverse clutches to enable the propeller to rotate in forward or reverse directions in accordance with the speed of the engine.
Typical prior art control means comprise two duplicate sets of manually operable control devices, one set for each drive system, located on the bridge of the vessel. A set of prior art control devices typically includes a manually actuatable speed control lever for controlling an engine throttle and a manually actuatable direction control lever for controlling the forward and reverse clutches of a transmission.
However, for convenience and safety, some vessels have two duplicate sets of such manually operable control devices, each set located at different command or navigation positions, such as on the main bridge and on the flying bridge or aft deck, to enable command from either position at any given time, either by one or more navigators. In the latter case, transfer of command from one position to another may require the sets of manually operable control devices at one command position to be returned to neutral so as to reduce the speed of both engines to idle and to disengage all clutches before command can be transferred to and assumed at the other position. As a result, the vessel slows down and is literally adrift while transfer occurs. In other cases, it is not possible to take command at another position without first issuing a command-enabling signal from the position currently in command. Obviously, hazardous situations can arise and become aggravated as a result of confusion and delay in transferring command.
Another disadvantage associated with prior art control systems for relatively large marine propulsion systems, is that it may be difficult or impossible to maintain a desired low vessel speed, even at engine idle, because the propeller shaft is coupled to the engine by a fully engaged clutch. In such a case propeller speed necessarily results in a vessel speed of about six to twelve knots, for example. Then, it is impossible to maintain a trolling speed substantially at or below the six knot speed limit often required in no-wake areas without a separate so-called trolling motor on the vessel.
Therefore, it is desirable to provide improved control means for marine propulsion systems to overcome and provide solutions to the problems described above.